The ruthenium aqua complexes [Ru(H(2)O)(2)(bipy)(2)](OTf)(2), [cis-Ru(6,6'-Cl(2)-bipy)(2)(OH(2))(2)](OTf)(2), [Ru(H(2)O)(2)(phen)(2)](OTf)(2), [Ru(H(2)O)(3)(2,2':6',2''-terpy)](OTf)(2) and [Ru(H(2)O)(3)(Phterpy)](OTf)(2) (bipy = 2,2'-bipyridine; OTf(-) = triflate; phen = phenanthroline; terpy = terpyridine; Phterpy = 4'-phenyl-2,2':6',2''-terpyridine) are water- and acid-stable catalysts for the hydrogenation of aldehydes and ketones in sulfolane solution. In the presence of HOS(O)(2)CF(3) (triflic acid) as a dehydration co-catalyst they directly convert 1,2-hexanediol to n-hexanol and hexane. The terpyridine complexes are stable and active as catalysts at temperatures > or = 250 degrees C and in either aqueous sulfolane solution or pure water convert glycerol into n-propanol and ultimately propane as the final reaction product in up to quantitative yield. For the terpy complexes the active catalyst is postulated to be a carbonyl species [(4'-R-2,2':6',2''-terpy)Ru(CO)(H(2)O)(2)](OTf)(2) (R = H, Ph) formed by the decarbonylation of aldehydes (hexanal for 1,2-hexanediol and 3-hydroxypropanal for glycerol) generated in the reaction mixture through acid-catalyzed dehydration. The structure of the dimeric complex [{(4'-phenyl-2,2':6',2''-terpy)Ru(CO)}(2)(mu-OCH(3))(2)](OTf)(2) has been determined by single crystal X-ray crystallography (Space group P1 (a = 8.2532(17); b = 12.858(3); c = 14.363(3) A; alpha = 64.38(3); beta = 77.26(3); gamma = 87.12(3) degrees, R = 4.36 %).

Crystal structures of six iodopyridinium tetrahalocuprate(II) salts are reported, (nIP) 2 CuX 4 , where X = Cl or Br, nIP is the n-iodopyridinium cation, and n = 2, 3, or 4. The supramolecular structure of these salts is developed based on N−H•••X hydrogen bonding and C−I•••X halogen bonding interactions. Comparing these structures with the previously published structures of the general formulas (nCP) 2 CuX 4 and (nBP) 2 CuX 4 , where nCP + and nBP + are the n-chloropyridinium and n-bromopyridinium cations, respectively, allows us to investigate the competition between the halogen and hydrogen bonding interactions. Henceforth, the general formula (nYP) 2 CuX 4 will be used to represent the 18 structures where nYP + is the n-halopyridinium cation. Isomorphism has been observed in these structures. Isomorphic structures are divided into four sets. Analysis of the isomorphic structures allows us to apply the separation of variables principle; upon comparison of isomorphic structures, complications arise from geometrical factors due to the isomeric nature of the nYP + cation and effects of intermolecular forces other than N−H•••X hydrogen bonding, and C−I•••X halogen bonding interactions are minimized and hence can be ignored. Comparing halogen and hydrogen bonding interaction parameters within each isomorphous set allows us to investigate the competition between these interactions. As the organic halogen becomes heavier and the halide ligand is unvaried, the N•••X distance is either unvaried or becomes longer. In contrast, the Y•••X distance becomes shorter even though heavier halogens have a larger radius. For example, for the isomorphous structures (2BP) 2 CuCl 4 and (2IP) 2 CuCl 4 , the N•••Cl distances are 2.926 Å and 3.070 Å, respectively, whereas the corresponding Y•••Cl distances are 3.322 Å and 3.316 Å. Theoretical calculations have shown that bifurcated hydrogen bonding interactions are stronger than the corresponding linear ones. Also, calculations have shown that as the organic halogen becomes heavier, the halogen bonding interactions become stronger. This agrees with crystal structure data; as the organic halogen gets heavier and the halide ligand is unvaried, the difference between the two legs of the bifurcated hydrogen bond becomes larger (weaker hydrogen bonding interactions). For example, the three (4YP) 2 CuBr 4 structures are isomorphous; the difference between the two legs of the hydrogen bond are 0.117 Å, 0.191 Å, and 0.246 Å for (4CP) 2 CuBr 4 , (4BP) 2 CuBr 4 , (4IP) 2 CuBr 4 , respectively. Surprisingly, the above two trends are valid in all isomorphous sets without exception, which is rare in solid state chemistry. Analysis of the Cu−X bond distances indicates that the Cu−X bond distance of the halogen acceptor is always shorter than that of the corresponding proton acceptor; which agrees with the theoretical calculations; hydrogen bonding interactions are stronger than the corresponding halogen bonding interactions.

The dibridgehead diphosphine ((CH)) P (1) can rapidly turn inside-out (homeomorphic isomerization) to give a mixture of in,in and out,out isomers. The exo directed lone pairs in the latter are able to scavenge Lewis acidic MCl; cagelike adducts of the in,in isomer, trans- Cl(P((CH)) P) (M = 2/Pt, 3/Pd, 4/Ni), then form. The NiCl unit in 4 may be replaced by PtCl or PdCl, but 2 and 3 do not give similar substitutions. U-tubes are charged with CHCl solutions of 1 (lower phase), an aqueous solution of KMCl (charging arm; M = Pt, Pd), and an aqueous solution of excess KCl (receiving arm). The MCl units are then transported to the receiving arm until equilibrium is reached (up to 22 d). When the receiving arm is charged with KCN, transport is much faster (ca. 100 h) and higher KMX equilibrium ratios are obtained (≥96≤4). Analogous experiments with KPtCl/KPdCl mixtures show PdCl transport to be more rapid. A similar diphosphine with longer methylene chains, P((CH))P, is equally effective. No transport occurs in the absence of 1, and other diphosphines or monophosphines assayed give only trace levels.

Isomers of the cage like dibridgehead diphosphine P((CH2)14)3P (1) are treated with Ph3PAu(2,6-C6H3(Trip)2) (2 equiv.; Trip = 2,4,6-C6H2(iPr)3). With out,out-1, workup gives out,out-1·(Au(2,6-C6H3(Trip)2))2 (46%), as confirmed by a crystal structure. With in,out-1, crystallization affords not in,out-1·(Au(2,6-C6H3(Trip)2))2, but rather an out,out isomer in which one of the (CH2)14 segments threads through the macrocycle formed by the other two. Implications for mechanisms of interconversion of in,out isomers are analyzed.